1. Field of the Invention
The present invention relates to a computer-peripheral device, capable of communicating wirelessly, that is a wireless computer-peripheral device.
2. Description of the Related Art
Ultra WideBand radio is used for wireless communication between computers and their peripherals. For instance, a CWUSB (Certified Wireless Universal Serial Bus) interface is an Ultra WideBand device, with which a suitably equipped computer can communicate wirelessly with a peripheral device incorporating another such interface. Existing laptops, not having CWUSB capability built in, can be retro-fitted with the capability by means of a CWUSB ExpressCard device, that is a card device in accordance with the ExpressCard standard of the Personal Computer Memory Card International Association—referred to herein as an ExpressCard card.
Ultra WideBand antennas can be formed from PCB traces in specific geometric patterns, but an unusual proximity effect has been observed when such an antenna is close to a planar surface comprised of non-metal material such as a table or desk of wood or plastic. This effect is distinct from attenuation that metal surfaces can cause. Antenna performance is significantly reduced when the active portion of the antenna is within 50 mm of the planar surface.
The height of an ExpressCard slot in a lap top computer is typically 15 mm above the surface on which the computer is placed, thus any antenna element in an ExpressCard card portion protruding from the computer's ExpressCard slot would be well within the zone in which antenna performance would be adversely affected.